The diurnal variation of terrestrial magnetism

Abstract

The diurnal variation of terrestrial magnetism has been the subject of experimental study for many years, and at a considerable number of observatories scattered all over the earth. But the co-ordination of the results, and the theoretical investigation of the physical cause or causes of the phenomena, have not made progress which seems to bear a reasonable proportion to the vast amount of observational data that has accumulated. As far as I know, Dr. Arthur Schuster’s memoirs constitute the most inspiring and systematic attempt to reduce this matter to scientific law and order. Although I have found it convenient to depart from the method pursued by Schuster, this change of procedure was in no small degree suggested by various remarks in his memoirs.